The benefit of using a coolant and/or cutting fluid for machining operations, cutting, etc. (generically referred to, herein, as machining) has long been appreciated by those having skill in the pertinent art. Coolants and cutting fluids (hereinafter simply coolants) first improve the performance of machining operation by cooling the workpiece and the cutting tool. Additionally, coolants lubricate the workpiece and cutting tool, thereby reducing frictional heat build-up. Further more, the use of coolants may also improve the removal of cut material by first inhibiting binding of the chips to the cutting tool, and further by flushing the chips of removed material from the work-site.
These effects provide several improvements to the process. The cutting force required to perform a given operation may be reduced allowing high cutting speeds to be used. Cooling of the workpiece and tool, as well as reduced frictional heating, in combination with the lower cutting force increased the life of the cutting tool. Also, the more efficient removal of cut material allows the generation of cut material at a higher rate, i.e., faster and/or deeper cutting, and also provides better control of the chips of removed material. All of these improvements facilitate an improved surface finish of the final part and increased workpiece accuracy, all while decreasing machining time.
Conventionally, coolants have been provided to a workpiece using hoses and nozzles that can be positioned manually. Such a system may generally include gooseneck hoses, or similar arrangements, originating from coolant pumps adjacent, or attached, to the machine tool. The gooseneck hoses include a nozzle on the free end thereof. The gooseneck hose may be positioned to direct a stream of coolant at a desired location on the workpiece or cutting tool.
Manually adjustable coolant systems are usually only suitable for providing relatively low pressure coolant streams. At higher pressures nozzles must be more rigidly held to prevent the nozzle from moving. However, rigidly fixing the nozzles increase the difficulty and time required to manually reposition the nozzle. Unfortunately, low pressure coolant streams are not as efficient for chip removal, and the flow rate of coolant through a given nozzle is also lower thereby reducing the available cooling capacity of the system. Penetration of coolant is also, at least somewhat, related to coolant pressure. Lower pressure coolant streams, therefore, have a lower ability to penetrate a cutting site.
For larger cutting envelopes numerous and frequent adjustments of the coolant streams are necessary to maintain the supply of coolant to the general vicinity of the cutting site. Repositioning of the coolant nozzles requires stopping the cutting operation and manually adjusting the gooseneck hose and nozzle to direct the coolant stream to the new desired location. Such repetitive stopping of the cutting process can greatly increase the time required to produce a finish article. Frustration resulting from such delays may often temp machine operators to reposition the coolant nozzles while the machine tool is still operating. The dangers of such practice are obvious.
Furthermore, coolant systems relying on manually positioned coolant nozzles reduce the benefits of modern automated machining. While the cutting path is computer controlled and does not require intervention by the operator, keeping the coolant directed to the cutting site may require the constant attention of an operator.
More recently, cooling systems have been developed that supply coolant to a cutting tool holder or chuck. Coolant may be supplied either through the spindle of the machine tool or from a collar fitted around the tool holder. Generally these systems provide coolant streams that are aimed at the cutting tool. However, such configurations result in the splashing coolant off of the cutting tool, and/or dispersing coolant from the centrifugal force of the rotation cutting tool. The end result is ineffective delivery of coolant to the working site. Also, such coolant delivery systems usually rely on complicated networks of cross passages for distributing coolant to ducts for delivering the coolant. These passages often require plugs and involve complicated machining operations.
Another variety of cooling systems actually supply coolant through the tool itself, via internal coolant passages in the cutting tool. The coolant is typically supplied to the cutting tool using through the spindle coolant delivery. The coolant passages in the cutting tool convey the coolant through the cutting tool to the distal tip of the cutting tool. Accordingly, coolant is discharged from the distal tip directly to the workpiece and cutting tool. However, this is only the case when cutting with the end face of the cutting tool, or when drilling blind holes. When cutting with the side of the tool, coolant is not directed at the cutting surface. Similarly, when completing through holes, the coolant discharged from the distal end of the cutting tool simply passes through the workpiece. Furthermore, because the cutting tools are cored out to provide coolant passages there-through, such cutting tools are weaker than conventional cutting tools. Through tool coolant cutting tools are also significantly more expensive than conventional cutting tools because of the complicated manufacturing processes required.